70. Number-line graphs. Observe the following conventions, which may already be familiar: • To indicate an interval on the number line, thicken that part of the number line.
• To indicate that an endpoint of an interval is included, place a solid dot on the number.
• To indicate that an endpoint is not included, place an open circle on the number. For example, the diagram illustrates those numbers that are greater than −2 and less than or equal to 3. ◦
• −2 3 Draw a number line for each of the following and indicate the numbers described: (a) All numbers that are exactly two units from 5.
(b) All numbers that are more than two units from 5.
(c) All numbers that are greater than −1 and less than or equal to 7.
(d) All numbers that are less than four units from zero.